Ford Motor Co. is preparing to wind down the Mercury line, created in 1939 by Edsel Ford, after sales plunged 74 percent since 2000, said two people familiar with the plan.

The automaker’s top executives are preparing a proposal to kill Mercury to be presented to directors in July, said the people, who asked not to be indentified revealing internal discussions. Mercury, losing two of four models next year, will be starved of products and promotion, the people said.